During major maintenance operations at refineries and chemical plants, it is often necessary for workers to enter and work inside tall generally cylindrical structures, known as vessels. These vessels typically are reactor vessels such as catalytic crackers, separation vessels such as crude units and the like. Because there is a substantial fire hazard inside the vessels, it has become common practice to provide a worker, called a fire watch, whose responsibility is keeping a lookout for fires and providing a first response in the event of a fire. The fire watch is equipped with an industrial sized fire extinguisher which must be delivered to the location where work is being conducted.
Because these type vessels are often quite tall, equipment such as industrial sized fire extinguishers are typically delivered by the hoist line of a crane or winch unit. In the past, a fire extinguisher was simply tied to a flexible line and hoisted to its desired location. Because a fire extinguisher has no obvious connections for a hoist line and because the workers on the ground tying the hoist line to the fire extinguisher have little or no experience in this exact problem, it is little wonder that fire extinguishers are periodically dropped during the hoisting operation. One can imagine the dangers in dropping a 50–100 pound load from great heights.
Disclosures of some interest relative to this invention are found in U.S. Pat. Nos. 2,440,712; 3,116,948; 3,351,371; 3,870,358; 5,645,129 and 5,816,331.